Is it a b-side? Posts about 'bside' typically mean "unreleased on album", or additional track. Ruby is on my USA version of Between The Buttons ... not to mention, i thought LSTNT and Ruby were more of "dual A-sides".
Anyway from the list above, I would go w/ one of these 7, not sure which would be my favorite:
Long Long While
Child Of The Moon
Let It Rock
Everything's Turning To Gold
Jump On Top Of Me
I could probably remove Let It Rock as I prefer the 1978 live versions.